Mr Pizzi, who has presented nature programmes on the BBC, Channel 4, Channel 5 and Animal Planet, told the 8th International Penguin Conference in Bristol about his keyhole surgery techniques, which help ensure the birds recover quickly.

The patients are members of the zoo’s colony of 70 gentoo penguins, which are renowned for being nosey and happy to gulp up anything they see in front of them.

“A penguin’s intestine is very compact, with sharp angles, and even an oak leaf can cause problems,” said Mr Pizzi, 38, who lives in Penicuik, Midlothian.

Due to the very inquisitive nature of our gentoo penguins, they do have a habit of eating things they shouldn’t, which is why we stress to our visitors to not throw objects into the enclosure

Romain Pizzi

“It is a very rare occurrence for animals at Edinburgh Zoo to swallow hazardous materials. However, due to the very inquisitive nature of our gentoo penguins, they do have a habit of eating things they shouldn’t, which is why we stress to our visitors to not throw objects into the enclosure.”

A spokeswoman for the zoo said: “All animals and birds, domestic or exotic, do tend to eat things they shouldn’t from time to time. Our keepers are extremely vigilant, but unfortunately the combination of wind, visitors and ultra-curious penguins has on the rare occasion led to one of our birds eating something they shouldn’t.”